Can I tune my 20 meter dipole to 40 meters?

[Singularity35]

I mean by using an antenna tuner. I seem to have a problem with my 40 meter dipoles. Seems that something is causing my 40 meter dipoles to go crazy after I install in my location. I'm planning on using a tuner to bandaid the problem until I can find a proper solution.

My 20 meter dipole is problem free, OTOH. So if I can tune it, it's going to be installed permanently rather than the 40 meter dipole.

 

[Beetle]

I mean by using an antenna tuner. I seem to have a problem with my 40 meter dipoles. Seems that something is causing my 40 meter dipoles to go crazy after I install in my location. I'm planning on using a tuner to bandaid the problem until I can find a proper solution.

My 20 meter dipole is problem free, OTOH. So if I can tune it, it's going to be installed permanently rather than the 40 meter dipole.

If you have a very good tuner (notice that the letters M, F and J do not appear in the phrase "good tuner"), you might be able to provide a match that will allow the transmitter to transfer most of what it generates into the feedline. You still have a very high impedance point right where the feedline connects to the antenna, however; the tuner can't change the antenna itself, even if the tuner is connected directly to the feedpoint.

How far apart are the 40M dipoles? You just may have some interaction between them. And FWIW, you won't get good performance using a 40M dipole on 20M, but a 40M dipole works reasonably well on 15M, if it's installed at the proper height for a 40M dipole.

 

[Singularity35]

Ahhh I have 2 40 meter dipoles and they were tuned in another location and just brought and installed in my location. They're not installed together. I tried putting one up and the SWR was dismal. Put the other one up and it was the same. I guess the best thing to do is to make and tune them at the location of installation. It seems there's something here that affects performance.

Anyway, I guess the 20 meter dipole will be used only for 20 meters. I do wonder though why the 20 meter dipole isn't being affected but the 40 meter ones are. I'm thinking the end points of the 20 are at a good enough distance from my roof but that the ends of the 40 meter one is too near. BTW, the dipoles are in a sort of inverted V config.